Control of dynamic stability during adaptation to gait termination on a slippery surface

Area of Science:

• Biomechanics
• Human locomotion
• Motor control

Background:

• Unexpected slips during gait termination trigger a generalized response to regain stability and prevent falls.
• Locomotor behavior can adapt with prior knowledge and experience of slippery surfaces to mitigate slip effects and enhance reactive control.

Purpose of the Study:

• To investigate the organizational strategies of adaptation to slippery surfaces during gait termination.
• To understand how knowledge and experience influence gait adjustments on slippery surfaces.

Main Methods:

• Participants (N=8) experienced unexpected slips during gait termination.
• Cued gait termination trials were conducted, providing participants with knowledge of surface characteristics (slippery or non-slippery).
• Gait parameters and muscle activity were analyzed to observe adaptive strategies.

Main Results:

• Adaptation to slippery surfaces involves proactively diminishing slip perturbation size via flattened foot placement, anterior center of mass (COM) shift, shorter steps, stance leg extension, and swing limb slowing.
• Reactive control is improved through decreased muscle activity and reduced braking force generation.
• These strategies collectively enhance stability and safety when stopping on slippery surfaces.

Conclusions:

• A combination of knowledge and experience with slippery surfaces enables both proactive and reactive behavioral adjustments.
• These adjustments are crucial for effectively and safely terminating gait on hazardous surfaces.
• Understanding these adaptations can inform interventions for fall prevention in challenging environments.